Mobile machines such as, for example, wheel tractor scrapers, dozers, motor graders, wheel loaders, and other types of equipment are used to perform a variety of earth-moving tasks. When performing such tasks, the mobile machine and its components may encounter vibrations and movements introduced by the vehicle itself and external inputs, such as dips and bumps of a worksite surface. An operator of the mobile machine may experience such vibrations, which may cause discomfort and difficulty controlling the vehicle. In order to improve operator comfort and vehicle control, for example, machines may typically employ suspension systems to help isolate the operator from the vibrations and various movements that may be experienced during machine operation. The suspension systems typically include a spring to support the machine component and a damper to control resonant motion of the seat.
In some instances, an initial vibration or acceleration caused by the vehicle or an external input may be isolated by the suspension system. However, subsequent and excess motion on the suspension may still disrupt the operator and make the mobile machine more difficult to control.
One method for improving the isolation of excess motion on a suspension is described in U.S. Pat. No. 5,276,622 (the '622 patent) to Miller et al., issued on Jan. 4, 1994. The '622 patent describes an end stop control method to control operation of an isolation system having an adjustable damper assembly. The end stop control method includes calculating a correct damping for sensed conditions based on kinematics of a suspension system. The damping system increases damping as the system approaches end stop limits. When a moving body, such as a seat, is likely to meet or exceed the end stop limits, a higher level damping routine is used to prevent harsh contact with the end stop limits.
Although the end stop method of the '622 patent may provide improved isolation of motion on a seat suspension, it may have limitations. For example, while the end stop method may isolate an initial disruption to the seat, it may not be able to adequately prevent operator discomfort or improve operator control of a machine in response to subsequent oscillations following the initial disruption. As a result, the seat suspension may undergo excess motion or “rattling,” making it difficult for the operator to maintain control of the machine and possibly causing operator discomfort.
The vibration control system of the present disclosure is directed towards improvements to the existing technology.